I've got an image that about 1100 pixels high at 250DPI. After opening that up in Vanishing Point, I lay out my grid on a building that's about 1000 pixels height.
Then I complete my grid with little difficulty. But after I Export my VPE data, my resulting PNG files are WAY too small! For example, the height of that 1000 pixel high building is now 186 pixels high.
I didn't think it would matter, but i tried to change my Grid size, and indeed, that had no affect.
Unfortunately, something wacky is happening.
As I said, my building that I'm placing the grid on is about 1000 pixels high at 240DPI. So I'd expect the resulting PNG files to be that too, but as mentioned, they are less than 200 pixels.
The way I noticed this was in AE, the images were all the right size, but looked bad. That tipped me off to look at the original PNG files and that's when I notice how small they were.
So PS/VPE made them small, AE blew them up 500%, so the building was large, but with artificially large images (scale increased).
So what I ended up doing was increasing the DPI (and resulting resolution) to 1200, which resulted in PNG files of about 980 pixels (high, in this case).
I just can't imagine what I'm doing wrong that the resulting PNG files are so small. It's very odd.